We are studying interactions between catecholamines (CA), behavior and the environment. We are interested in learning how biogenic amine metabolism is controlled and how these controls respond to particular demands placed on the animals, demands such as changes in the internal (e.g., drug state, food deprivation) and external (e.g., foot shock stress, operant schedules of reinforcement, temperature) environments, as well as the demands necessitated by recovery from partial destruction of the amine-containing fiber systems. At the same time we are trying to gain some understanding of the role these amines play in central neural functioning. These studies all utilize male albino rats. Specific experiments now in progress include: (1) A study of the in vitro metabolism of tyrosine as a function of precursor and product concentration and the effects of certain drugs, (2) A study of rate- dependent effects of drugs on operant behavior, and (3) A study of the effects of biochemically - or electrolytically- induced lesions on homeostatic regulatory processes (including their behavioral components) as a function of time after the lesion is produced.